Can I connect my iPod classic or universal dock with optical

Well, no... not at least with the Apple docks.

Optical Audio is also called S/PDIF. It is a purely digital signal designed for specific kinds of home theater and HIFI systems. ℹ

The iPod classic does not have such a connection... that being said, HOWEVER

There are some iPod docks that use S/PDIF out.

http://www.cambridgeaudio.com/summary.php?PID=605&Title=Summary ℹ

Does this help you? 😉

Just wanted to add that you can output your iPod music to S/PDIF from that cambridge audio doc (link I posted)

Also, iPad can connect to a USB DAC either through a USB hub or via direct from the camera connection kit for USB-A Ansynchronus USB for digital sound.